Based on the principle of 2FSK modulation and demodulation, Simulink models for 2FSK modulation and demodulation were established with the Simulink software tools, and simulation analysis was carried out. Simulation results showed that the waveform variations of the signals were consistent with theoretical analysis, indicating that the design was reasonable and the system was effective. Finally, with Additive White Gaussian Noise (AWGN), the bit error rate (BER) of three 2FSK demodulation systems, namely coherent demodulation system, envelope detection system and zero crossing detection system, were analyzed. It was found that when the signal-to-noise ratio (SNR) was large, bit error free transmission could be achieved, while as the signal-to-noise ratio decreased, the bit error rate increased. This paper has certain guiding significance for communication system design and experimental teaching.